The prior magnetic read/write apparatus described in U.S. Pat. No. 4,445,157, as shown in FIG. 2, has the construction that a spindle hub 17 is directly secured at a spindle 14 of a spindle motor 13, a disk hub 2 including a magnetic disk 1 within a disk cartridge 3 is brought in contact with a spindle hub 17 directly by a magnetic attraction and the engaging portion between a guide hole 62 and a motor spindle 14 is positioned so as to guide the motor spindle radially relative to the magnetic disk. Further, a driving pin 21 for driving the magnetic disk 1 is constructed at the periphery of the guided portion radially.
However, in the prior magnetic read/write apparatus since the magnetic disk is radially guided relative to the spindle, the motor spindle has such a shape as an end of the spherical surface and an inclined portion in order to insert it easily. Furthermore, the larger the diameter of the motor spindle is made to secure the strength and the positioning accuracy, the more clearance is required, making it impossible to provide a small-sized magnetic read/write apparatus. Moreover, since the driving pin is constructed at the periphery of the motor spindle, it is difficult to provide a small-sized media hub and a small-sized spindle hub. Therefore, it is difficult to increase the data storage capacity with securing the magnetic disk at a wide area, and the contacting portion between the magnetic dish and the magnetic head (hereinafter referred to as the head contact) is operated rigidly on appearance thus, is not well fit for the device, making it impossible to obtain an excellent magnetic read/write characteristics.
Therefore, to solve the above problems, the object of the present invention is to provide a small-sized spindle hub and a small-sized media hub and provide a magnetic read/write apparatus possible of an excellent head contact.